Preparation of Potassium Nitrate

Preparation of Potassium Nitrate. Pour 25 ml of water into a beaker and dissolve 12 g of sodium nitrate in it upon heating. Add an equivalent amount of potassium chloride to the solution. Cover the beaker with a watch glass and heat it on a gauze with a small burner flame until crystals precipitate. Can crystals form without evaporation of the solution Rapidly pour the hot liquid into a porcelain bowl and let it stand until crystals form. 

Substance Solubility at temperature Substance Solubility at temperature  

Potassium nitrate Sodium chloride 21 36 246 40 Potassium chloride Sodium nitrate 31 81 56 174 

---

Use is made of this double decomposition in the technical preparation of potassium nitrate from Chih saltpetre. Four salts connected by an equation of the above kind are caUed reciprocal pairs of salts. A further example of this kind is the manufacture of sodium bicarbonate by the Solvay process, viz. 

Nitric acid is prepared in the laboratory by distilling equal weights of potassium nitrate and concentrated sulphuric acid using an air condenser, the stem of which dips into a flask cooled by tap water. The reaction is ... 

To prepare fervenulin 4-oxides 12 or toxoflavine 4-oxides 146, it is convenient to use the reaction of l,3-dimethyl-2,4-dioxopyrimidin-6-yl hydrazone 147 or N-(3-methyl-2,4-dioxopyiimidin-6-yl) iV-methylhydrazone 148 with potassium nitrate in acetic acid [75CPB1885,76CPB338,76JCS(CC)658,82JHC1309,93CPB362]. Diethyl azodicarboxylate can be used instead of potassium nitrate [76JCS(P1 )713]. 

Procedure (a). Prepare the indicator by grinding 0.1 g murexide with 10 g of potassium nitrate use about 50 mg of the mixture for each titration. 

Nitric acid may be produced by several methods. In the laboratory, it is prepared by distilling a solution of potassium nitrate in concentrated sulfuric acid containing equal amounts (by weight) of each.. 

Sodium and potassium nitrates are soluble in liquid ammonia,38 and the soln. are good electrical conductors. According to F. M. Raoult, the dry salts absorb no ammonia, but a cone. soln. of sodium nitrate dissolves as much ammonia as an equal volume of water, and a cone. soln. of potassium nitrate, more ammonia than water. R. Abegg and H. Riesenfeld found the tension of N, N-, and l 5A-soln. of potassium nitrate in A-soln. of ammonia at 25°, had vap. press. 14 59, 15 61, and 16 75 mm. respectively, when the A-ammonia alone had a vap. press, of 13 45 mm. F. Ephraim prepared lithium tetrammino-nitrate, LiN03.4NH3, as a syrup more stable than the corresponding tetrammino-chloride. The electrical conductivities and the lowering of the f.p. of soln. of potassium nitrate 39 in soln. 

Preparation of Potassium Nitrite. Melt 1-2 g of potassium nitrate in a test tube and heat it above its melting point until oxygen bubbles stop evolving. Dissolve the cooled substance in water and add 1-2 ml of a dilute sulphuric acid solution. What happens ... 

Preparation of Potassium Chromate. (Perform one experiment on each table.) Melt a mixture of 1 g of potassium carbonate, 1 gof potassium hydroxide, and 2 g of potassium nitrate in an iron crucible by heating with the flame of a burner. While stirring the melt with an iron wire, introduce 1 g of finely comminuted chromite or -0.8 g of chromium oxide into the crucible. Roast the mixture for 5-10 minutes on a blowpipe. Treat the cooled melt with water. Filter the solution and evaporate it until a crystalline film appears. What is the composition of the formed crystals Why was potassium carbonate introduced into the reaction Write the equation of the reaction. 

Preparation of Potassium Manganate. Melt a mixture of 1 g of potassium hydroxide, 2 g of potassium carbonate, and 3 g of potassium nitrate in an iron crucible on a gas burner. While stirring the liquid mixture with an iron wire, add 1 g of powdered manga-nese(IV) oxide in small portions. Continue the heating while stirring until the substance becomes thick. After it cools, treat the melt in the crucible with a small amount of water. Pour off the transparent solution into a small flask and close it with a stopper keep the substance remaining in the crucible for the following experiment. What is the colour of the solution What substance colours it Write the equation of the reaction. 

Nitrites. — Dissolve 1 gm. of potassium nitrate in 20 cc. of water, acidulate with 1 cc. of 16 per cent sulphuric acid, and add 1 cc. of a freshly prepared, colorless 1 200 solution of metaphenylenediamine hydrochloride. No yellow or yellowish-brown color should develop. 

Sulfur is determined as the further loss of weight on extraction with carbon disulfide in a Wilcv extractor or other suitable apparatus. After the extraction, the crucible ought to be allowed to dry in the air away from flames until all the inflammable carbon disulfide has escaped. It is then dried in the oven to constancy of weight, and the residue is taken as charcoal. Ash is determined by igniting the residue in the crucible until all carbon has burned away. A high result for ash may indicate that the water extraction during the determination of potassium nitrate was not complete. The analytical results may be calculated on a moisture-free basis for a closer approximation to the formula by which the manufacturer prepared the powder. 

For amounts of potassium nitrate higher than o-i% the reaction is sharp and intense. A feeble coloration with brucine or a slightly colomed ring with ferrous sulphate should be neglected, since extracts may derive traces of mtnc anhydride from the water used m their preparation, such quantities, however, never amount to o-i% of the extract... 

Table 5.1 shows an application of XPS to the study of the promoted iron catalyst used in the Haber synthesis of ammonia. The sizes of the various electron intensity peaks allows a modest level of quantitative analysis. This catalyst is prepared by sintering an iron oxide, such as magnetite (Fe304) with small amounts of potassium nitrate, calcium carbonate, aluminium oxide and other trace elements at about 1900 K. The unreduced solid produced on cooling is a mixture of oxides. On exposure to the nitrogen-hydrogen reactant gas mixture in the Haber process, the catalyst is converted to its operative, reduced form containing metallic iron. As shown in Table 5.1, the elemental components of the catalyst exhibit surface enrichment or depletion, and the extent of this differs between unreduced and reduced forms. 

Name at least three oxidizing agents which might have been used instead of potassium nitrate in this preparation, and write equations. 

O A saturated solution of potassium nitrate was prepared at 70°C and then cooled to 55°C. Use your graph from Investigation 8-A to predict the fraction of the dissolved solute that crystallized out of the solution. 

Ruthenium Dioxide (by Pichler).190 A mixture of 1 g of ruthenium powder, 10 g of potassium hydroxide, and 1 g of potassium nitrate is fused in a silver (or a nickel) crucible. It is recommended that the potassium nitrate be added not simultaneously but in portion after portion. In 1-2 h the fusion is complete. After cooling, the mass is dissolved with water into a solution. The dark red solution of potassium ruthenate is heated to boiling, and methanol is added to this dropwise. Immediately after the first drop of methanol has been added, the reduction of the ruthenate to ruthenium dioxide takes place and the reduction is completed in a few minutes. After leaving the precipitate for 1-2 h, the precipitate is collected on a glass filter, washed 7 times with a dilute nitric acid solution and then 18 times with distilled water, and dried at 110°C for 24 h in a desiccator. Pichler s dioxide thus prepared does not show any distinct diffraction patterns corresponding to the oxide of ruthenium and is partly soluble into hot concentrated hydrochloric acid. These facts suggest that Pichler s dioxide is a mixture of the oxide and the hydroxide of ruthenium.191... 

The salt may be prepared in an impure form by dissolving ruthenium in fused potassium hydroxide, adding small quantities of potassium nitrate the while, until all the ruthenium has passed into solution. On cooling the green mass becomes orange, and treatment with concentrated hydrochloric leaves a residue of potassium chlor-ruthenite.8... 

No. II. Thirty-eight parts of combination of honey and glycerine, 19 of potassium chlorate, 24 of potassium nitrate, 10 of prepared sawdust, and 9 of prepared chalk. 

Summary TNT can be made by reacting a 99% nitric acid/methylene chloride mixture with toluene in the presence of 98% sulfuric acid. The 99% nitric acid/methylene chloride mixture is prepared by extracting a mixture of potassium nitrate or sodium nitrate and sulfuric acid. The reaction mixture is then treated with water, and then filtered to collect any precipitated TNT. The upper methylene chloride layer is then decanted, and evaporated to yield dry solid of TNT. The TNT is then purified by mixing it with 70% sulfuric acid. The acidic mixture is then filtered to collect the TNT, which is then washed with water, and then dried. 

---